Strange Alternator Problem ( I think)

[adv5500]

on '99 ranger xlt 3.0L
I've been getting my battery light on the dash going on when my engine is pushing between 2500-3000 rpm. I think this must be due to the alternator, but I'd think that the alternator would be having problems at low idle and not at this level rpm. I tested the battery and it's fine and alternator is fine at low idle. Has anyone else had this problem?

 

[Nhaz]

The alternator puts out more then 12-20 volts. The faster it goes the more its going to crank out.

The regulator brings the voltage back down and keeps it between the voltage range of about 12-16 volts.

The battery light should come on if the voltage is too low Or too high. So I think the regulator is down on your alternator.

a test would be to put a volt meter on the battery while rpm'ing the engine up. if the voltage gets beyond 16-18 volts you have a problem.

 

[shadetree]

Actually you don't want the voltage over 15 vdc. Stuff starts to overheat above that voltage, and yes you need to test your battery voltage at all speed. It sounds as if you may have belt slippage at that engine speeds..shady

 

[adv5500]

Actually you don't want the voltage over 15 vdc. Stuff starts to overheat above that voltage, and yes you need to test you batter voltage at all speed. It sounds as if you may have belt slippage at that engine speed..shady

interesting, i just replaced my serpentine belt last week.

 

[86ford]

interesting, i just replaced my serpentine belt last week.

Is the belt tensioner functioning properly?

Figure out if that vehicle has a replaceable regulator.

86

 

[adv5500]

Is the belt tensioner functioning properly?

Figure out if that vehicle has a replaceable regulator.

86

The tensioner felt as if it was working just fine. Bit I'm not going to rule anything out. I don't feel this is a huge problem because im rarely pushing 3k rpms for more than a minute or two. But if its something easy, i'll check anything out.
i wonder how to figure out if it has a replaceable regulator.

 

[oldjohnny]

I'd say belt tensioner.

You'd be surprised. I once almost changed my AC compressor because it wasn't clicking in. Turns out my belt tensioner was the problem. If you go off roading and you get the belt wet, you'll see your bat meter do some crazy stuff.

 

[Scrambler82]

If you can't test it go to a local auto parts store and have them test both the Alternator and the battery under load.

At 3000 the belt could be slipping and as others have already said check the tensioner, not sure how that is done.

After having the auto parts store check it out you can at least eliminate those two things.

luck,

 

[adv5500]

Well, the battery wasn't charging at any rpm today and the battery died shortly after that. I tested the battery and obviously it wasn't doing so hot and the alternator just wasn't working at all. I replaced the alternator and it solved all problems. It's still strange the way it went out. So the alternator I got was a valuecraft from autozone.... how can anyone charge 130 dollars for a refurbished alternator, its sickening.

 

[Earl43P]

Not really.
I've worked on alts and starters.
I figure my time is worth at least $20/hr.
Throw parts, materials, tools, overhead (electricity, rent) and shipping on there along with that clerk's wages, etc and it isn't that unreasonable.

 

[adv5500]

Not really.
I've worked on alts and starters.
I figure my time is worth at least $20/hr.
Throw parts, materials, tools, overhead (electricity, rent) and shipping on there along with that clerk's wages, etc and it isn't that unreasonable.

130 was for the part, I put it in myself.